McCartin announced his decision to retire from the AFL at the end of the 2019 season following ongoing issues with concussion.
The 24-year-old has been cleared for a return to the league after ongoing tests with AFL concussion experts and is eyeing off a spot on an AFL list for 2021.
Speaking on SEN Breakfast, Koschitzke, who has battled concussion issues following his retirement, warned McCartin of a return.
“It’s a tough one as I’m not privy to what is going on with him and the medical side of things and advice he is getting,” Koschitzke told SEN Breakfast.
“Brain injuries can be terrible in later life and I’m experiencing that firsthand. I would really encourage him to make a really intelligent decision and not go on.
“I’ve got really bad memory loss and bad mood swings and down times. I have no doubt it’s from the concussions.
“I certainty feel after the hit in 2006 I changed as a person. I really reckon it affected my personality.
“I have to really watch myself, be careful of what I’m doing and work on myself. No doubt it has had a big impact.
“This is what Paddy should be looking at. He might feel fresh and fine now, but it’s the long-term impacts. You look at guys who had some big knocks in their 40s and 50s, I’m certainly concerned about that with the older I get.”
List sizes are set to take a hit as an outcome of the coronavirus despite several clubs looking to add to their key forward stocks.